Determination of Disconnecting Switch Ratings for the Pennsylvania-New Jersey-Maryland Interconnection

This paper presents principles and procedures to be used by member companies of the Pennsylvania-New Jersey-Maryland Interconnection to establish normal and emergency thermal ratings for non-enclosed disconnecting switches affecting the Interconnection. The resulting ratings can be used for selecting the most economical nameplate ratings for new disconnecting switches. Disconnecting switches built under C37.30-19622 and prior standards and also C37.30-197X2 are included. A complete review was made of switch characteristics, thermal loading, and rating methods. The rating method is presented in the form of formulas, nomographs and tables for determination of switch ratings. All companies of the Interconnection have agreed upon the rating determinations to ensure consistent ratings for any given disconnecting switch application.